42 THE CANADIAN NATURALIST. [Feb. 



the external circumstances in which they have been placed have 

 not varied. For all practical purposes, therefore, the characters 

 on which species are found may be assumed to be constant; and a 

 minute and careful description of a plant will suffice, not only for 

 the present, but for many succeeding generations of naturalists. 

 But we have no warrant from nature to assume that such specific, 

 or even generic, characteristics either have been, or will continue to 

 be, permanent for an unlimited period of time, that they will survive 

 all future changes in the physical geography of the planetary sur- 

 face. We know that great changes may be effected in a brief 

 space of time in the organization of plants by cultivation ; and 

 why should not an organic change be brought about in plants 

 when their external circumstances are altered by nature in the 

 course of ages ? This world, what is it but a great and ancient 

 theatre where the scenery of life is ever changing ? Look at that 

 majestic and venerable tree; its present form appears to be fixed, 

 yet that very form is in reality as fleeting and evanescent as all 

 the other forms through which that tree has passed from its first 

 life movement in the seed ; and what is true of that tree, which is 

 a part of nature, is true of the whole of nature. The present ap- 

 pearance of nature now is no more unalterable than at any other 

 geological epoch. It is the last of the many phases of creation, 

 and equally fleeting with all the others. — Popular Science Review. 



ON THE GRAPTOLITES OF THE QUEBEC GROUP. 



By Professor James Hall. 



[This long-expected monograph* is now before us, and has grown 

 in magnitude under the delays which have attended its publication, 

 until, instead of one decade, it contains no less than twenty-three 

 admirable plates, with one hundred and fifty pages of letter-press. 



Prof. Hall gives to the Graptolitidce the rank of a family, 

 including fifteen genera, of which no less than eleven occur in the 

 Quebec group, this being, so far as known, the period of the 

 greatest development of these curious organisms. The species 



* Decade II of Canadian Organic Remains, issued by the Geological 

 Survey of Canada. Dawson Bros., Montreal ; Balliere, London, New 



